This specification relates to online content distribution.
The Internet provides access to a wide variety of resources. For example, video and/or audio files, as well as web pages for particular subjects or particular news articles, are accessible over the Internet. Access to these resources presents opportunities for other content (e.g., advertisements) to be provided with the resources. For example, a web page can include slots in which content can be presented. These slots can be defined in the web page or defined for presentation with a web page, for example, along with search results.
A publisher's web page may have multiple slots, e.g., for displaying content items, such as advertisements, on the publisher's web page. Each of the slots can have associated publisher-specified parameters by which eligible content items are to be selected to fill the slots. Example parameters can be related to the size of the slot, the content format (e.g., one or more of text, image, video, etc.), the content type (e.g., dogs, vacations, sports, etc.) and/or other parameters.
Content items can be selected for presentation to a user based on, among other things, previous behavior. A web page may include code, such as in the form of a small transparent image, that causes a browser to convey information to a server upon requesting the image. The conveyed information can be used for various purposes, such as in selecting content for presentation to a viewing entity.